The Clown Prince of Crime
Super Freak
I really don't remember Indy without his jacket in Crystal Skull.
The intro sequence in the military base/nuke fridge. I can't think of which film he wore the jacket the most, probably Crystal Skull. Having said that, the Intro of Raiders is probably the most famous moment/sequence of any of the Indy films and he wore the jacket. In second place, I'd say Indy shooting the swordsman without the jacket.